The discovery of an M4+T8.5 binary system

Burningham, B.; Pinfield, D. J.; Leggett, S. K.; Tinney, C. G.; Liu, Mengmeng; Homeier, D.; West, Andrew A.; Day-Jones, A. C.; Huélamo, N.; Dupuy, Trent J.; Zhang, ZH; Murray, D. N.; Lodieu, N.; Barrado, D.; Folkes, S. L.; Galvez-Ortiz, M. C.; Jones, H. R. A.; Lucas, P. W.; Calderon, M. Morales; Tamura, Motohide

doi:10.1111/j.1365-2966.2009.14620.x

Cited by 106 publications

(122 citation statements)

References 73 publications

(137 reference statements)

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“…Assuming a luminosity 0.5 mag brighter leads to a luminosity function twice smaller in these bins. However, the T8.5 dwarf found around a M 4 dwarf with measured parallax (Burningham et al 2009, open square in Fig. 7) tends to show that the late-T dwarfs luminosity is not underestimated, on the contrary.…”

Section: The Luminosity Function Of Systemsmentioning

confidence: 96%

“…Three latest dwarfs at the boundary between T and Y dwarfs give the high density 8.3 +9.0 −5.1 × 10 −3 objects pc −3 , although the uncertainties are very large and the luminosity function is still consistent with being flat. Since then, at least three ultracool brown dwarfs (>T8) have also been discovered in UKIDSS (Burningham et al , 2009) that currently probes a slightly higher but comparable volume for late-T dwarfs. Even if these combined statistics still deal with a low number of objects, this could indicate that the number of ultracool brown dwarfs found by the CFBDS is not entirely due to a fluke of statistics and that many of these objects remain to be discovered in the solar neighbourhood.…”

Section: Discussionmentioning

confidence: 99%

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The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

Reylé

Delorme

Willott

et al. 2010

A&A

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Context. Thanks to recent and ongoing large scale surveys, hundreds of brown dwarfs have been discovered in the last decade. The Canada-France Brown Dwarf Survey is a wide-field survey for cool brown dwarfs conducted with the MegaCam camera on the Canada-France-Hawaii Telescope. Aims. Our objectives are to find ultracool brown dwarfs and to constrain the field brown-dwarf luminosity function and the mass function from a large and homogeneous sample of L and T dwarfs. Methods. We identify candidates in CFHT/MegaCam i and z images and follow them up with pointed near infrared (NIR) imaging on several telescopes. Halfway through our survey we found ∼50 T dwarfs and ∼170 L or ultra cool M dwarfs drawn from a larger sample of 1400 candidates with typical ultracool dwarfs i − z colours, found in 780 square degrees. Results. We have currently completed the NIR follow-up on a large part of the survey for all candidates from mid-L dwarfs down to the latest T dwarfs known with utracool dwarfs' colours. This allows us to draw on a complete and well defined sample of 102 ultracool dwarfs to investigate the luminosity function and space density of field dwarfs. Conclusions. We found the density of late L5 to T0 dwarfs to be 2.0 +0.8 −0.7 × 10 −3 objects pc −3 , the density of T0.5 to T5.5 dwarfs to be 1.4 +0.3 −0.2 × 10 −3 objects pc −3 , and the density of T6 to T8 dwarfs to be 5.3 +3.1 −2.2 × 10 −3 objects pc −3 . We found that these results agree better with a flat substellar mass function. Three latest dwarfs at the boundary between T and Y dwarfs give the high density 8.3 +9.0 −5.1 × 10 −3 objects pc −3 . Although the uncertainties are very large this suggests that many brown dwarfs should be found in this late spectral type range, as expected from the cooling of brown dwarfs, whatever their mass, down to very low temperature.

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Section: The Luminosity Function Of Systemsmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

Reylé

Delorme

Willott

et al. 2010

A&A

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“…The latest-type brown dwarfs with trigonometric parallaxes available are the T8.5 dwarfs Wolf 940B at a distance of 12.5 ± 0.7 pc (=ULAS J214638.83-001038.7;Burningham et al 2009; with a parallax measurement for the primary Wolf 940A by Harrington & Dahn 1980) and ULAS J003402.77−005206.7 Smart et al 2009) at a distance of 12.6 ± 0.6 pc. Gelino et al (2009) list only one more T8.5 (ULAS J123828.51+095351.3; Burningham et al 2008) and two T9 dwarfs (ULAS J133553.45+113005.2; Burningham et al 2008 and CFBDS J005910.90−011401.3;Delorme et al 2008a), which are still lacking trigonometric parallaxes.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Whereas the latest-type (coolest) objects discovered in the 2MASS are of spectral type T8 (Burgasser et al2002;Tinney et al 2005;Looper et al 2007), a handful of even cooler (T eff ≈ 500-600 K) brown dwarfs (T8.5-T9) have already been discovered in UKIDSS Burningham et al 2008Burningham et al , 2009) and CFBDS (Delorme et al 2008a) that do not look conspicuously different in their near-infrared spectra from latetype T dwarfs. A unique Y dwarf has not yet been found and classified.…”

Section: Introductionmentioning

confidence: 99%

ULAS J141623.94+134836.3 – a faint common proper motion companion of a nearby L dwarf

Scholz¹

2010

A&A

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Aims. New near-infrared large-area sky surveys (e.g. UKIDSS, CFBDS, WISE) go deeper than 2MASS and aim at detecting brown dwarfs lurking in the solar neighbourhood that are even fainter than the latest known T-type objects, so-called Y dwarfs. Methods. Using UKIDSS data, we found a faint brown dwarf candidate with very red optical-to-near-infrared, but extremely blue near-infrared colours next to the recently discovered nearby L dwarf SDSS J141624.08+134826.7. We checked if the two objects are co-moving by studying their parallactic and proper motion and compared the new object with known T dwarfs. Results. The astrometric measurements are consistent with a physical pair (sep ≈ 75 AU) at a distance d ≈ 8 pc. The extreme colour (J − K ≈ −1.7) and absolute magnitude (M J = 17.78 ± 0.46 and M K = 19.45 ± 0.52) make the new object appear as one of the coolest (T eff ≈ 600 K) and nearest brown dwarfs, probably of late-T spectral type and possibly with a high surface gravity (log g ≈ 5.0).

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“…Saumon et al 2007). Burningham et al (2009) use luminosity to determine T eff for the T8.5 Wolf 940B, and show that an analysis using synthetic spectra alone would have overestimated the temperature by ∼100 K, for this 600 K object.…”

Section: Introductionmentioning

confidence: 99%

The distance to the cool T9 brown dwarf ULAS J003402.77-005206.7

Smart¹,

Jones

Lattanzi³

et al. 2010

A&A

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Aims. We demonstrate the feasibility of determining parallaxes for nearby objects with the Wide Field Camera on the United Kingdom Infrared Telescope (UKIRT) using the UKIRT Infrared Deep Sky Survey as a first epoch. We determine physical parameters for ULAS J003402.77-005206.7, one of the coolest brown dwarfs currently known, using atmospheric and evolutionary models with the distance found here. Methods. Observations over the period 10/2005 to 07/2009 were pipeline processed at the Cambridge Astronomical Survey Unit and combined to produce a parallax and proper motion using standard procedures. Results. We determined π = 79.6 ± 3.8 mas, μ α = −20.0 ± 3.7 mas/yr and μ δ = −363.8 ± 4.3 mas/yr for ULAS J003402.77-005206.7. Conclusions. We have made a direct parallax determination for one of the coolest objects outside of the solar system. The distance is consistent with a relatively young, 1−2 Gyr, low mass, 13−20 M J , cool, 550−600 K, brown dwarf. We present a measurement of the radial velocity that is consistent with an age between 0.5 and 4.0 Gyr.

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The discovery of an M4+T8.5 binary system

Cited by 106 publications

References 73 publications

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

The ultracool-field dwarf luminosity-function and space density from the Canada-France Brown Dwarf Survey

ULAS J141623.94+134836.3 – a faint common proper motion companion of a nearby L dwarf

The distance to the cool T9 brown dwarf ULAS J003402.77-005206.7

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